If you're a customer of Telstra's GameArena or Games Shop site, you won't be able to log in using your existing password today. Customer data for 35,000 users of the service was stolen in a hacking attack, so Telstra has reset the passwords as a precaution.
A statement from Telstra outlines the extent of the impact:
Information that might have been obtained was limited to BigPond Games usernames, the email address used to join the site and the encrypted GameArena and Games Shop passwords of up to 35,000 customers.
Telstra says it is emailing details of the new password to affected customers; if you haven't received an email, you can click here to have your password reset. Update More than 230,000 passwords were reset following the attack.
According to Telstra, the site is operated by a third party, so other Telstra customers shouldn't be affected. It also said that no credit card details were stored on the affected server.
As ever, if you used the same password for GameArena as for other sites, you should change that password on other sites as well. Using the same password on multiple sites is an elementary security mistake you should avoid, but it happens.